Pressure-Viscosity Measurements for Several Lubricants to 5.5 × 10<sup>8</sup>Newtons Per Square Meter (8 × 10<sup>4</sup>PSI) and 149 C (300 F)

Jones, William; Johnson, Robert L.; Winer, W. O.; Sanborn, D. M.

doi:10.1080/05698197508982767

Cited by 78 publications

(19 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In 1973, Hutton and Phillips [5] employed a Couette viscometer to demonstrate faster-thanexponential response to refute the incorrect slower-thanexponential behavior that had been derived from an EHL film-thickness analysis based on Newtonian viscosity. Jones et al [6] in 1975 found faster-than-exponential response at low pressures for two lubricating oils with a capillary viscometer. Piermarini et al [7] in 1978 and later Cook et al [8] used diamond anvil cells as dropping ball and rolling ball viscometers, respectively, to observe the inflection in simple liquids such as methanol.…”

Section: The Behavior Observed In Viscometersmentioning

confidence: 99%

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

2016

View full text Add to dashboard Cite

Ninety years of high-pressure measurements with many different types of viscometers have shown that faster-than-exponential (super-Arrhenius) pressure dependence of viscosity is universal for glass-forming liquids and, therefore, all typical liquid lubricants. Dielectric spectroscopy at elevated pressure also yields super-Arrhenius response in the dependence on pressure of the primary relaxation time. In contrast, classical elastohydrodynamic lubrication (EHL) has gone to great lengths to ignore this phenomenon, including fictional accounts of the results of viscometry. As a result of this, classical EHL is unable to quantitatively account for one of the most important properties affecting friction at low sliding velocity, the low-shear viscosity. Differences in friction between similar liquids at low sliding velocity can be explained by their different inflection pressures. Some observed liquid response to shear stress at high pressure can be explained with the measured super-Arrhenius pressure dependence. It should be clear that, had classical EHL employed realistic pressure dependence of viscosity from its beginning, the field would have been in a better position today to solve engineering problems which involve the differences among molecular structures.

show abstract

Section: The Behavior Observed In Viscometersmentioning

confidence: 99%

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

2016

View full text Add to dashboard Cite

show abstract

“…Winer (26) has advocated the use of another pressure-viscosity parameter, the i reciprocal asymptotic isoviscous pressure (a*) based on work by Roelands (36). Pressure 6 viscosity coefficients (_*) (26) for three temperatures (38, 99, and 149°C) are tabulated in Table 4 , Therefore, lubricants possessing high _ values (i.e., K fluids) in this range would be preferred, when only considering EHL.…”

Section: Viscosity-temperature Propertiesmentioning

confidence: 99%

Properties of Perfluoropolyethers for Space Applications

Jones

1995

Tribology Transactions

Self Cite

View full text Add to dashboard Cite

“…This misconception originates from early work using high-pressure capillary viscometers which are very susceptible to viscous heating at high shear stress. Only in the 1970s did it become evident that because of thermal effects capillary viscometers are not suited to measure viscosities at high shear stresses [4]. However, as described in [1], in EHD contacts the linear shear-log strain rate response only becomes evident at high shear stresses after a correction is applied to negate the effect of viscous heating and is thus most certainly not a product of the latter.…”

mentioning

confidence: 99%

Reply to the ‘Comment on “The Relationship Between Friction and Film Thickness in EHD Point Contacts in the Presence of Longitudinal Roughness” by Guegan, Kadiric, Gabelli, & Spikes’ by Scott Bair

et al. 2017

View full text Add to dashboard Cite

We must confess to being surprised and dismayed that our paper on the impact of bearing roughness on friction has aroused such passion as to warrant a Comment from Professor Bair.Bair's Comment is ostensibly an expression of concern that we applied a mean shear stress analysis to match our smooth surface data with the Eyring shear thinning model of lubricant viscosity rather than integrating over the varying pressure of the EHD contact. He is indeed correct that for this quite low pressure steel/glass contact we should have integrated and this would have resulted in a higher calculated Eyring shear stress and a different alpha. He makes much of the importance of using a non-Barus viscosity pressure equation and highlights the Yasutomi model. In fact, at these low pressures and the test temperature there is little difference between the viscosities calculated using the Yasutomi and Barus models.As we understand it, Bair's argument is mainly based on the idea that by varying only the Eyring stress it is not possible to fit our measured friction data for a smooth contact with an integrated model if we use the quoted alpha value of 19.2 GPa -1 . Here there might be a slight misunderstanding; both this value of alpha and the Eyring stress were found by fitting the non-integrated argsinh model. When we use these parameters and integrate over the contact area assuming a Hertz distribution of pressure, we find indeed that these predict a lower friction that does not match the friction measurements. However, as shown in Fig. 1, it is perfectly possible to find quite reasonable values of alpha and the Eyring stress that enable us to match the integrated model with our data.Bair's Comment then segues into a general criticism of the Eyring shear thinning model to which he has long taken exception. This issue has been fully discussed in [1-3] and need not be revisited here except to note that at the end of his Discussion, Bair suggests that the linear shear versus log strain rate behaviour characteristic of Eyring shear thinning results from viscous heating and that this has been mistaken for a non-Newtonian response. This misconception originates from early work using high-pressure capillary viscometers which are very susceptible to viscous heating at high shear stress. Only in the 1970s did it become evident that because of thermal effects capillary viscometers are not suited to measure viscosities at high shear stresses [4]. However, as described in [1], in EHD contacts the linear shear-log strain rate response only becomes evident at high shear stresses after a correction is applied to negate the effect of viscous heating and is thus most certainly not a product of the latter.We shall ignore Bair's intemperate Conclusion. In his Appendix (which appears to have little relevance to his overall Comment) Professor Bair takes exception to the attribution to Barus of the well-known exponential dependence of viscosity on pressure, pointing out that Barus fitted a linear equation to his viscosity data on marine glue. In his pape...

show abstract

Pressure-Viscosity Measurements for Several Lubricants to 5.5 × 10⁸Newtons Per Square Meter (8 × 10⁴PSI) and 149 C (300 F)

Cited by 78 publications

References 12 publications

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

Properties of Perfluoropolyethers for Space Applications

Reply to the ‘Comment on “The Relationship Between Friction and Film Thickness in EHD Point Contacts in the Presence of Longitudinal Roughness” by Guegan, Kadiric, Gabelli, & Spikes’ by Scott Bair

Contact Info

Product

Resources

About

Pressure-Viscosity Measurements for Several Lubricants to 5.5 × 108Newtons Per Square Meter (8 × 104PSI) and 149 C (300 F)

Cited by 78 publications

References 12 publications

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

Classical EHL Versus Quantitative EHL: A Perspective Part II—Super-Arrhenius Piezoviscosity, an Essential Component of Elastohydrodynamic Friction Missing from Classical EHL

Properties of Perfluoropolyethers for Space Applications

Reply to the ‘Comment on “The Relationship Between Friction and Film Thickness in EHD Point Contacts in the Presence of Longitudinal Roughness” by Guegan, Kadiric, Gabelli, & Spikes’ by Scott Bair

Contact Info

Product

Resources

About

Pressure-Viscosity Measurements for Several Lubricants to 5.5 × 10⁸Newtons Per Square Meter (8 × 10⁴PSI) and 149 C (300 F)